The reaction of β-enaminoesters with organolithium reagents: a convenient method for the regioselective synthesis of enaminoketones

A simple and practical method for the regioselective preparation of β-enaminoketones is described. The method relies on the reaction of β-enaminoesters with organolithium reagents, and allows the preparation of a range of unusual β-enaminoketones.     

Rearrangement of N-Allyl-α,α-dichloroamides, β- or γ- Functionalized,to Substituted Analogues of the γ-Aminobutyric Acid (GABA)

The rearrangement of γ-chlm, β-hydroxy or β-vmyl N-allyl-N-benzyl-α,α-dichlorocarboxyamides to γ-aminobutynic acid analogues is efficiently promoted by CuCI\N,N,N′,N′-tetramethylethylendiamine. With the β-vinyl functionalization a tandem radical-radical reaction, yieldmg 3-aza-2-oxo-bicyclo[3,3,0]actatre adducts, is also observed.     

Direct Visualisation of the Surface Atomic Active Sites of Carbon-Supported Co3O4 Nanocrystals via High-Resolution Phase Restoration

The atomic arrangement of the terminating facets on spinel Co₃O₄ nanocrystals is strongly linked to their catalytic performance. However, the spinel crystal structure offers multiple possible surface terminations depending on the synthesis. Thus, understanding the terminating surface atomic structure is essential in developing high-performance Co₃O₄ nanocrystals. In this work, we present direct atomic-scale observation of the surface terminations of Co₃O₄ nanoparticles supported on hollow carbon spheres (HCSs) using exit wavefunction reconstruction from aberration-corrected transmission electron microscopy focal-series. The restored high-resolution phases show distinct resolved oxygen and cobalt atomic columns. The data show that the structure of {100}, {110}, and {111} facets of spinel Co₃O₄ exhibit characteristic active sites for carbon monoxide (CO) adsorption, in agreement with density functional theory calculations. Of these facets, the {100} and {110} surface terminations are better suited for CO adsorption than the {111}. However, the presence of oxygen on the {111} surface termination indicates this facet also plays an essential role in CO adsorption. Our results demonstrate direct evidence of the surface termination atomic structure beyond the assumed stoichiometry of the surface.     

Effect of compatibilization on thermal degradation kinetics of HDPE-based composites containing cellulose reinforcements

Dynamic thermogravimetric analysis under nitrogen flow was used to investigate the thermal decomposition process of high-density poly(ethylene) (HDPE)-based composites reinforced with cellulose fibers obtained from the recycling of multilayer carton scraps, as a function of the cellulose content and the compatibilization. The Friedman, Flynn–Wall–Ozawa, and Coats–Redfern methods were used to determine the apparent activation energy (E _a) of the thermal degradation of the cellulose component into the composites. E _a has been found dependent on the cellulose amount and on the cellulose/polymer matrix interfacial adhesion. In particular, it has been evidenced an increase of the cellulose thermal stability as a consequence of the improved interfacial adhesion between the components in NFR composites.     

Shape-dependent plasmon resonances of Ag nanostructures

Different silver nanostructures have been rapidly synthesized under microwave irradiation from a solution of silver nitrate (AgNO₃) and β$\beta$-D glucose; neither additional reducing nor capping agent were required in this soft green solution approach. Not only spherical nanoparticles, but also necklace and wires have been synthesized. The plasmon resonances of the synthesized silver nanostructures were tuned by varying the irradiation time and hence by changing size and morphology of nanostructures. The obtained nanostructures were characterized by X-Ray diffraction (XRD), Uv–Vis spectroscopy (Uv–Vis), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The change of peak position and the shape of the absorption spectra were clearly observed during the whole reaction process; in fact, it was evidenced that initially Ag nanoparticles were formed, which, as reaction time elapsed, self-assembled and fused with each other to yield nanowires.     

Synthesis and matrix-assisted laser desorption/ionization time-of-flight characterization of bisphenol-A copolyformals containing nickel(II)/Schiff base, eicosane and 2-butene units in the main chain

Some bisphenol-A copolyformals, containing in the main chain different amounts of a Ni-diimine nonlinear optical (NLO)-chromophore, eicosane and/or 2-butene units, were synthesized by condensation reaction between dibromomethane and suitable mixtures of Ni(II)/Schiff base complex, 1,20-di(bisphenol-A)ether-eicosane and/or 1,4-di(bisphenol-A)ether-2-butene. Structural composition and thermal properties of polymeric materials were inferred by analyses by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermogravimetry (TG). MALDI-TOF data show that both Ni-diimine and unsaturated units are present in the copolyformals with a homogeneous arrangement in all the polymer mass range (GPC data). It has also been ascertained that the glass transition temperature (Tg) of the copolymers changes as a consequence of the abundance of aliphatic units in the macromolecules (DSC data). Cross-linking experiments of the copolymer at temperatures near the Tg value and under UV irradiation were also performed.     

p1,n1 salts: Self-assembled supramolecular structures sequestering racemates. Diastereomeric separation and enantiomeric enrichment of trans-chrysanthemic acid

The occurrence of p1,n1 salts can be exploited to sequester racemates; an application to technical mixtures of chrysanthemic acids (ChA) allowed the separation of trans- and cis-ChA and the recovery of the excess enantiomer of trans-ChA.     

Phase diagram of patchy colloids: towards empty liquids

We report theoretical and numerical evaluations of the phase diagram for patchy colloidal particles of new generation. We show that the reduction of the number of bonded nearest neighbors offers the possibility of generating liquid states (i.e., states with temperature T lower than the liquid-gas critical temperature) with a vanishing occupied packing fraction (phi), a case which can not be realized with spherically interacting particles. Theoretical results suggest that such reduction is accompanied by an increase of the region of stability of the liquid phase in the (T-phi) plane, possibly favoring the establishment of homogeneous disordered materials at small phi, i.e., stable equilibrium gels.     

Robust return risk measures

In this paper we provide an axiomatic foundation to Orlicz risk measures in terms of properties of their acceptance sets, by exploiting their natural correspondence with shortfall risk Föllmer and Schied (Stochastic finance. De Gruyter, Berlin, 2011), thus paralleling the characterization in Weber (Math Financ 16:419–442, 2006). From a financial point of view, Orlicz risk measures assess the stochastic nature of returns, in contrast to the common use of risk measures to assess the stochastic nature of a position’s monetary value. The correspondence with shortfall risk leads to several robustified versions of Orlicz risk measures, and of their optimized translation invariant extensions (Rockafellar and Uryasev in J Risk 2:21–42, 2000, Goovaerts et al. in Insur Math Econ 34:505–516, 2004), arising from an ambiguity averse approach as in Gilboa and Schmeidler (J Math Econ 18:141–153, 1989), Maccheroni et al. (Econometrica 74:1447–1498, 2006), Chateauneuf and Faro (J Math Econ 45:535–558, 2010), or from a multiplicity of Young functions. We study the properties of these robust Orlicz risk measures, derive their dual representations, and provide some examples and applications.